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A possibility of an implementation of Mach-Zehnder and Michelson interferometers for formation laser pulses with periodic intensity modulation is considered analytically.

Theoretical model of scanning cross-correlator used for diagnostic 3D profiled laser pulses was developed. The parameters of nonlinear crystals and the required accuracy of its alignment for correct measurements were determined with help of based on the model numerical simulations.

Modern linacs are considered for generation of THz pulses with up to mJ energies at high repetition rates due to the capabilities of modern photo injectors. A Self-Amplified Spontaneous Emission (SASE) FEL is proposed for such a powerful THZ source [1]. In order to improve the Carrier-Envelope-Phase (CEP) stability of the THz SASE FEL a seeding option using temporally modulated electron bunches from the photo injector is under study. One of the methods is to generate electron beams with a sub-picosecond structure. Modern linac based FELs (like the European XFEL at DESY and LCLS at SLAC) start from photo injectors, where electron bunches are generated by laser pulses from a cathode surface. In this case, the phase space distribution of the electron bunches strongly depends on the 3D spatio-temporal intensity distribution of the photocathode laser pulses. So, it is necessary to modulate the temporal intensity distribution of the laser pulses to obtain rippled (or microbunched) electron beams. Spectral phase or spectral amplitude modulation of linearly chirped laser pulses can be used to obtain laser pulses with ∼1 ps modulation period. A spatial light modulator (SLM) placed inside the optical compressor with zero frequency dispersion is an attractive way to produce the modulation [3, 4].

Modern photoinjectros require to use 3D profiled laser pulses for irradiation of cathode surface. The pulses make it possible to control a space-charge distribution of generated electron bunches and, in paritcular, to form electron bunches with cylindrica and 3D ellipsoidal shapes. Spatial light modulators (SLM) [1,2] and profiled volume Bragg gratings [3] can be used for control 3D intensity distribution of linearly chirped broadband infrared laser pulses. But, the widely used in photoinjectors Cs 2 Te photocathodes have the highest efficiency in UV spectral range. So, the important task is to transform the profiled 3D (x,y,t) infrared pulses to visible and UV regions with high energy conversion efficiency and preserving 3D intensity distribution. It can be done with help of second, fourth and third harmonic generation (SHG, FHG, THG) processes at low group velocity mismatch of the interacted pulses. The control of the group velocities can be done by a creation of amplitude tilt or angular chirp. Here we present results of numerical simulations of SHG, FHG and noncollinear THG processes implemented for laser pulses with central wavelength 744 nm, 6 nm spectral width (FWHM) and pulse duration 15 ps (FWHM). The initial fundamental pulse has ellipsoidal 3D shape with linear grouth intensity in time.

Possibility of effective fourth harmonic generation with preserving of a shape of linearly chirped IR laser pulses with triangular temporal intensity profile has been demonstrated numerically.